US6566894B2 - Process and device for detecting oxidizable and/or reducible gases in air - Google Patents

Process and device for detecting oxidizable and/or reducible gases in air Download PDF

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US6566894B2
US6566894B2 US09/183,376 US18337698A US6566894B2 US 6566894 B2 US6566894 B2 US 6566894B2 US 18337698 A US18337698 A US 18337698A US 6566894 B2 US6566894 B2 US 6566894B2
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sensor
frequencies
gases
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Hanns Rump
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/122—Circuits particularly adapted therefor, e.g. linearising circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/0037—NOx
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/004—CO or CO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

  • the invention relates to a method for detection of oxidizable and/or reducible gases in the air for the purpose of controlling devices for ventilation in buildings or vehicles and for the purpose of surveillance of combustion processes or of waste gas catalyst plants, by employing at least one heated and current-passing sensor, furnished with contact electrodes and made of a metallic sensor material, as well as by employing an electrical evaluation circuit, wherein the sensor is passed through by an alternating current, which alternating current either comprises at least two alternating currents of different frequencies or is switched between at least two frequencies, and wherein, on the one hand, the change of the capacitances between the sensor material and the contact electrodes is evaluated by the evaluation circuit as an indicator of a presence of reduceable gases and, on the other hand, the change of the capacitances within the mass of the sensor material (sensitive material) is evaluated as an indicator of the presence of oxidizable gases, as well as to a device for the performance of the method.
  • metal oxide sensors change their electrical resistance upon presence of a gas.
  • the generally known sensors consist of a heated and contacted layer made for example of tin dioxide or of another metal oxide such as, for example, zinc oxide, gallium oxide, tungsten trioxide, aluminum vanadate, and other sensitive materials, wherein the sensor material is applied in a thin film technique or a thick film technique to a substrate made of ceramics or silicon and exhibits contact electrodes. If an oxidizable gaseous material impinges onto the sensor, then the metal oxide releases oxygen and becomes therefore reduced, whereby the conductivity value is increased. This process is reversible because the heated metal oxide combines later again with the oxygen of the air.
  • the conductivity value of the sensor material is a function of the concentration of the oxidizable gases present, since a continuous exchange process is present between the offered gas, the metal oxide and the oxygen of the air and because the concentration of the oxygen of the air is a quasi constant value.
  • An electrically reactive compound device has in addition become known from the U.S. Pat. No. 5,387,462, which compound device exhibits random and regular fields of microstructures, which are in part disposed within an enveloping layer, wherein each microstructure exhibits a structure similar to a hair crystal and possibly exhibits a cover layer, wherein the cover layer envelopes the hair-crystal-like structure.
  • the compound device is electrically conducting and serves as a component of an electrical switching circuit, of an antenna, of a micro-electrode, as a reactive heating element, or as a multimode sensor, in order tQ prove a presence of vapors, gases or liquids.
  • the change of the orientation of the hair-like crystals is employed for measuring a presence of the material to be detected.
  • the solution of the object resides with respect to a method in that the sensor is passed through by an alternating current, which alternating current consist either out of at least two alternating currents of different frequency is or which alternating current is switched between at least two frequencies, wherein on the one hand the change of the capacities between the sensor material and the contact electrodes is evaluated as being typical for the presence of reducible gases and on the other hand the change of the capacitances within the mass of the sensor material (sensitive material) is evaluated as typical for the presence of oxidizable gases, and wherein the changes of the Ohmic resistance components of the sensor material are considered in connection with the changes depending on the gas.
  • the sensor can be a component of an oscillator circuit for the generation of two different frequencies, wherein the oscillation of the oscillator circuit is periodically changed by switching the frequency-determining components between at least two frequencies, wherein the respective frequencies are individually evaluated and are compared to the respective frequencies determined during operation of the sensor in standard air and frequency deviations are employed as a measure for the concentration of present gas groups, wherein high frequencies are always coordinated to reducible gases and wherein low frequencies are always coordinated to oxidizable gases.
  • the phase shifts caused by the sensor-internal capacities are determined at the individual frequencies, and the output signal is decomposed into an imaginary part and into a real part, which imaginary part and real part represent a measure for the presence and for the kind of gases relative to the values determined under standard air conditions.
  • the temperature of the sensor can be switched simultaneously with the switching of the frequencies, wherein the lower frequency is coordinated to the higher temperature and wherein the higher frequency is coordinated to the lower temperature.
  • a device is characterized in that the sensor is passed through by alternating current, which alternating current consists of at least two alternating currents of different frequencies or which is switchable between at least two frequencies, wherein on the one hand the change of the capacities between the sensor material and the contact electrodes is evaluated as typical for the presence of reducible gases and on the other hand the change of the capacities within the mass of the sensor material (sensitive material) is evaluated as typical for the presence of oxidizable gases, and wherein the gas-dependent changes of the Ohmic resistance components of the sensor material are considered in context.
  • the advantage of the method and of the device for this purpose comprise that both gas groups, namely oxidizable gases as well as reducible gases can be detected simultaneously with one and the same sensor, such as a metal sensor, in particular the conventional metal oxide sensors, wherein the device can be produced under favorable cost conditions.
  • the invention is based on the observation that the reaction mechanisms of oxidizable gases or of reducible gases, which are capable of being electrically evaluated, are substantially different.
  • oxidizable gases for example of carbon monoxide CO
  • the Ohmic conductivity value of the mass of the sensor material changes as such by the reduction of the material.
  • the transition capacitance at the crystal transitions (path resistance) within the material are changed in a significant way.
  • the transition capacitance at the contacts is changed hardly at all.
  • the sensor reacts differently when reducible gases, for example nitrogen oxide NO or nitrogen dioxide NO 2 are absorbed at the surface of the sensor material. Based on the lower reactivity, a lower change of the electrical parameters of the sensor mass (path resistance) or, respectively, of the sensor material occurs than in the case of oxidizable gases. However, a substantial influencing of the Schottky transitions occurs caused by the gas-induced boundary face states.
  • reducible gases for example nitrogen oxide NO or nitrogen dioxide NO 2
  • the invention furnishes therefore a device which allows the simultaneous detection both of oxidizable substances and of reducible substances with one single sensor, wherein the changes of the above described capacitances are employed and exploited, which changes are a function of the nature of the gas.
  • FIG. 1 shows an electrical equivalent circuit diagram of a sensor with tin dioxide as a sensor material as a combination of resistors and capacitors;
  • FIG. 2 shows an expanded, more precise electrical equivalent circuit diagram according to FIG. 1 based on the addition of contact capacitances and resistances of the contact electrodes;
  • FIG. 3 shows two courses of the impedance, namely curve 3 . 2 showing the course of the impedance of the contact transition, and curve 3 . 1 showing the course of the impedance within the polycrystalline structure of the path resistance with larger capacities;
  • FIG. 4 shows the simplified equivalent circuit diagram of the sensor consisting only of a capacitor and of a resistor
  • FIG. 5 shows a technical realization of a device with not too high a claim to the precision of the measurement
  • FIG. 6 shows the measurement results from the circuit according to FIG. 5 presented as a curve
  • FIG. 7 shows a technical realization of a device with a high precision of the measurement
  • FIG. 8 shows a curve for the real part of the sensor resistance according to the device of FIG. 7 in the presence of five parts per million of nitric oxide NO 2 in synthetic air, plotted over the time axis.
  • FIG. 9 shows a parallel connection of the two capacitors as a frequency determining cuircuit and which comprises a ‘real’ switching element.
  • FIG. 10 shows a curve for the imaginary part of the sensor resistance according to the device of FIG. 7 in the presence of five parts per million of nitric oxide NO 2 in synthetic air, plotted over the time axis.
  • the electrical resistance of a metal oxide sensor is obtained on the one hand from the mass of the sensitive metal oxide and its Ohmic resistance or, respectively, the specific resistance.
  • Schottky transitions with contact capacitances are already present between the individual crystals of the actual polycrystalline metal oxide as a function of the grain size and the thickness of the material, wherein the contact capacitances are switched sequentially and parallel. Transitions are obtained upon transition to the contact electrodes, which transitions are to be understood also as Schottky transitions with corresponding switching capacitances which is illustrated in FIG. 1 by way of a equivalent circuit diagram.
  • a preferred sensor is made of a mixed oxide including tin dioxide (SnO 2 ) plus tungsten trioxide (WO 3 ) plus zinc oxide (ZnO) plus iron trioxide (Fe 2 O 3 ).
  • these components are employed with the following weight percentages:
  • Tin dioxide from about 40 to 50 weight percent
  • Tungsten trioxide from about 35 to 45 weight percent
  • Zinc oxide from about 10 to 20 weight percent
  • Iron trioxide from about 2 to 10 weight percent
  • a preferred composition contains 45 weight percent tin dioxide, 40 weight percent tungsten trioxide, 15 weight percent zinc oxide, and 5 weight percent iron trioxide.
  • the heatable sensor is preferably heated to temperatures from about 200 to 400° C. and more preferably to temperatures from about 300 to 350° C. and a practical value for such temperature can be 330° C.
  • the temperature regions of the lower temperature and of the higher temperature of the sensor during switching of frequencies can be from about ⁇ 10 to 100° C. and is preferably from about ⁇ 30 to 50° C. with a practical value of ⁇ 30° C. difference employed in practical examples.
  • a sensor can be obtained commercially from the company FIGARO Inc., Osaka, Japan, which sensor carries the type designation TGS 812.
  • FIG. 2 illustrates a more precise equivalent circuit diagram of the model according to FIG. 1, wherein R 1 represents the volume part of the resistance, R 2 represents the transition resistance of the metal oxide to the contacts, and C 2 represents the capacitance at the Schottky transitions; resistor R 3 and capacitor C 3 describe the gas-dependent diffusion and migration effects of the sensitive material at the electrical transitions within the polycrystalline material of the sensor.
  • the capacitances at the contact transitions can be determined to be 10 to 100 pF, while the capacitances at the Schottky transitions of the grain boundaries within the material can assume values of 0.1 to 2 ⁇ F depending on the grain size and the layer thickness.
  • the equivalent circuit diagram of the sensor is roughly simplified as consisting of a series circuit of a single capacitor 4 . 2 and of a single resistor 4 . 1 in each case for the contact transition or, respectively, for the polycrystalline mass, there result impedance courses (capacity plotted versus the frequency) such as they are shown in FIG. 3 .
  • the course of the curve 3 . 2 is in this case the course of the impedance of the contact transition, the capacitances of which are substantially smaller and the capacitances of which take care of an impedance decreasing with the frequency up to a relatively high frequency.
  • the Ohmic part of the series-connected path resistance prevails at very high frequencies such that the curve assumes an asymptotic course.
  • FIG. 5 shows a technical realization of the device with not too high a claim to the precision of the measurement, which has proven itself for many purposes and which is sufficient.
  • a sensor 5 . 1 heated to a temperature of, for example, 350° C. is a component of an oscillator circuit 5 . 8 , preferably, the sensor 5 . 1 with its contact electrodes 5 . 9 and 5 . 10 is disposed parallel to the oscillator circuit 5 . 8 .
  • the output signal of the oscillator circuit 5 . 8 at the output 5 . 10 is applied to a micro-processor 5 . 5 ( ⁇ P).
  • a capacitor 5 A capacitor 5 .
  • capacitor 5 . 3 is connected in series to a capacitor 5 . 3 and connected with the one input 5 . 9 of the oscillator circuit 5 . 8 or, respectively, with the one contact electrode 5 . 9 of the sensor 5 . 1 , wherein the capacitor 5 . 3 can be short-circuited alternatingly or, respectively, periodically.
  • the switching frequency can be from about 2 hz to 100 hz and is preferably from about 5 hz to 20 hz and can be for example 10 hz.
  • the alternating short-circuiting of the capacitor 5 . 3 can for example occur in a field-effect transistor 5 . 4 , wherein for example in a p-channel barrier-layer field effect the drain or, respectively, the source connection 5 . 6 is disposed centered between the capacitors 5 . 2 and 5 . 3 , which is connected to the mass; the gate connection 5 . 7 is connected to the microprocessor 5 . 5 ( ⁇ P).
  • the field effect transistor 5 . 4 is controlled by the microprocessor 5 . 5 .
  • the circuit is laid out such that a frequency of about 3 to 5 khz of the oscillator circuit 5 . 8 results upon a short circuit of the capacitor 5 . 3 when the sensor 5 .
  • the internal counter of the microprocessor 5 . 5 determines also the frequency delivered by the oscillator circuit 5 . 8 .
  • the input capacitances of the oscillator circuit 5 . 8 is changed correspondingly by a continuous switching of the field effect transistor 5 . 4 between short circuit of the capacitor 5 . 3 and the series connection of the capacitors 5 . 3 and 5 . 2 , whereby the output frequency of the oscillator circuit 5 . 8 is changed.
  • the ratio of the respective operating times is a selected such that the number of oscillations, read into the counter of the microprocessor 5 . 5 , approximately correspond to each other. Since the frequencies have a ratio of about 1:30, the control ratio of the field effect transistor will be selected to be about 30:1.
  • the change in capacitance in case of full saturation amounts to from about 10 to 30 percent and can assume a value Delta-C of 20 percent.
  • the change in capacitance amounts to form about 30 to 70 percent and can assume a value of Delta-C of 50 percent.
  • the micro-processor reads in each case the counter and coordinates the results in each case to a channel such that a picture is generated according to the picture shown FIG. 6 .
  • a curve 6 . 1 represents the results of the high frequency signals (o . . . ) and the other curve 6 . 2 represents the low frequency signals (x . . . ).
  • the high frequency signals 6 . 1 are influenced to a substantially higher degree by the nitrogen oxides and other reducible gases as compared to the low frequency signals 6 . 2 , which for practical purposes are only influenced by oxidizable gases. Since the reactions are counter running, the distance 6 . 3 of the signals (- . . .
  • -) from each other is a measure for the sum of the gases present, which can be fully sufficient for example in regard to questions of the ventilation control of buildings or of motor vehicle cabins.
  • the ventilation flap of a motor vehicle can be closed in cases where for example the distance 6 . 3 surpasses a defined size measure.
  • a stationary signal is employed, which signal reliably detects for an unlimited time for example in tunnel situations an unusually high loading of the air.
  • the method according to be present invention is superior to known methods for the simultaneous detection of diesel waste gases and of gasoline waste gases because the known methods operate dynamically and do not generate any signals in case of a permanent level of the gas and for example would again open the ventilation flap in a tunnel extremely loaded with waste gases, which is not always desired.
  • the amounts of change are considered by a weight depending on the response sensitivity to the respective defined object gases, for which corresponding technologies are known, and these technologies are therefore not considered in the framework of the invention.
  • it is of highest interest in connection with the determination of combustion processes to know the respective parts of oxidizable gases and of nitrogen oxides.
  • the deviation from the “zero line” characterizes the concentration of that respective gas, which can be evaluated by the microprocessor with a program installed for that purpose.
  • the method can be employed with the success also for on-board diagnoses (OBD) of motor vehicle catalysts, since the sensors are sturdy and economic and since the evaluation electronics also does not involve special requirements.
  • OBD on-board diagnoses
  • the presented switching circuit example is only one of a multitude of possibilities.
  • the basic idea according to the invention includes to switch the alternating current, employed for the evaluation, back and fourth between two frequencies and to evaluate the obtained data such that one information gives the sum of the gases present or, respectively, the concentration of the oxidizable gases present and of the reducible gases present, by capturing the specific changes at the respective frequencies in comparison to standard air with a suitable electronic evaluation circuit.
  • the two alternating currents of different frequencies within the sensor can be selected between 1 hz and 1 MHz, and are preferably between 100 hz and 10 khz.
  • the frequency of the alternating current having a higher frequency can be from about 2 to 10,000 times the value of the frequency of the alternating current having a lower frequency and is preferably from about 10 to 1,000 times the frequency of the alternating current having a lower frequency.
  • FIG. 7 shows a technical realization of a device with high measurement precision.
  • the signal is decomposed into the real part and into the imaginary part in each case for each frequency by a phase consideration with the aid of a suitable comparison circuit according to the state of the art.
  • the information obtained in this manner is more precise than the previously described method in connection with FIG. 5 but requires somewhat higher expenditures.
  • an alternating current from a generator 7 . 1 is fed to a sensor 7 . 2 through a phase shifter 7 . 3 and a rectangular wave modulator 7 . 4 , which generator 7 . 1 is capable of generating alternating currents of different frequencies.
  • the output signal of the rectangular wave modulator 7 . 4 and the voltage, tapped through the sensors 7 . 2 are fed to a mixer 7 . 5 , for example a multiplier, wherein the output signal of the multiplier is averaged over a low pass 7 . 6 .
  • the output voltage 7 . 7 obtained after the low pass 7 . 6 , represents, depending on, the setting of the phase shifter 7 . 3 , a measure for the imaginary part and for the real part or for a mixture of the two components of the complex sensor resistor (compare the principle of the phase-proper rectifier pp.).
  • the thus enabled separation of the real part and of the imaginary part of the complex sensor resistor permits the distinction of capacitive and resistive effects at the sensor 7 . 2 .
  • This allows the distinction or, respectively, the simultaneous measurement of gases, which gases are distinguished by different reaction mechanisms at different places of the sensor, namely at the grain boundaries or at the metal semiconductor contact.
  • several absorption effects and change charge effects with in part opposite results on the real part on the sensor resistor can occur upon the adsorption of gases on semiconductor sensors (HL-sensors), which renders a quick and reliable detection of the gas difficult.
  • FIG. 8 and FIG. 10 show two curves for the real part and for the imaginary part of the sensor resistance according to the device of FIG. 7 in the presence of 5 ppm NO 2 in synthetic air, applied over a time axis.
  • the employment of the imaginary part of the sensor resistor can lead in this case to a higher detection reliability and to a quicker detection.
  • the imaginary part and the real part of the sensor resistance of a metal oxide sensor are plotted in FIG. 8 and FIG. 10 relative to the time in minutes in case of the presence of 5 ppm nitrogen dioxide NO 2 in synthetic air.
  • the curves were plotted with an arrangement according to FIG. 7 with an applied sinus voltage of 0.1 volts and a frequency of 50 khz.
  • the real part of the sensor resistance shows two oppositely directed effects and could be used for a reliable evaluation only ten minutes after the start of the presence of the gas
  • the imaginary part of the sensor resistor shows from the beginning of the presence of the gas an unequivocal and evaluatable change in direction and reaches already after about 6.5 minutes 90 percent of its final change.
  • the sensitivity relative to nitrogen oxides is very high at low temperatures of, for example, 150° C., while the sensitivity relative to carbon monoxide, etc. decreases. This effect is substantially supported by the precedingly described methods.
  • the stability of the arrangement increases, since no migration effects and no ion transport are to be observed any longer and also possibly included water molecules are no longer electrically dissociated at the high frequencies coordinated to the low temperatures, which is advantageous for the service live and the stability of the sensor elements.
  • sensor materials can be advantageously employed, where the sensor materials allow a higher operating temperature.
  • Mixed oxides with a high content of tungsten dioxide, gallium oxide are advantageously proven.
  • Vanadates and molybdates have also been tested as admixtures.
  • the low cross sensitivity relative to water is advantageously recited in connection with high operating temperatures and the recited sensitive materials.
  • the invention method and the apparatus can be employed in particular for the quantitative and qualitative determination of gases, wherein the gases are oxidizable or reducible, in particular for the purpose of controlling ventilation plants in buildings and motor vehicles and for the purpose of monitoring combustion processes and waste gas catalyst plants.
  • the usefulness of the invention comprises in particular that a statement relative to the presence and to the concentration of oxidizable gases can be made based on the change of the electrical path resistance of the sensor, and a statement relative to the presence and to the concentration of reducible gases with the aid of the electrical evaluation arrangement can be made based on the change of the electrical contact resistance.

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JP19617297.7 1996-04-30
DE19617297 1996-04-30
DE19617297A DE19617297A1 (de) 1996-04-30 1996-04-30 Simultane Detektion von oxidierbaren und reduzierbaren Gasen mit Metalloxidsensoren unter Einsatz von Impedanzspektroskopie
PCT/EP1997/002208 WO1997041423A1 (de) 1996-04-30 1997-04-29 Verfahren zur detektion oxidierbarer und/oder reduzierbarer gase in der luft sowie vorrichtung hierzu

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US20060218989A1 (en) * 2005-03-30 2006-10-05 Dominic Cianciarelli Method and apparatus for monitoring catalytic abator efficiency
US20060260737A1 (en) * 2005-03-31 2006-11-23 Maximilian Fleischer Gas-sensitive field-effect transistor with air gap
US20060278528A1 (en) * 2005-04-01 2006-12-14 Maximilian Fleischer Method of effecting a signal readout on a gas-sensitive field-effect transistor
US20070181426A1 (en) * 2004-04-22 2007-08-09 Maximilian Fleischer Fet-based sensor for detecting reducing gases or alcohol, and associated production and operation method
US20070220954A1 (en) * 2004-04-22 2007-09-27 Micronas Gmbh Fet-Based Gas Sensor
US20070235773A1 (en) * 2005-03-31 2007-10-11 Ignaz Eisele Gas-sensitive field-effect transistor for the detection of hydrogen sulfide
US20080198524A1 (en) * 2007-02-16 2008-08-21 Dometic Corporation Absorption gas arrestor system
US7553458B2 (en) 2001-03-05 2009-06-30 Micronas Gmbh Alcohol sensor using the work function measurement principle
US7812622B1 (en) * 2002-09-09 2010-10-12 Yizhong Sun Sensor and method for detecting analytes in fluids
US7946153B2 (en) 2004-04-22 2011-05-24 Micronas Gmbh Method for measuring gases and/or minimizing cross sensitivity in FET-based gas sensors
US7992426B2 (en) 2004-04-22 2011-08-09 Micronas Gmbh Apparatus and method for increasing the selectivity of FET-based gas sensors
US20140212979A1 (en) * 2013-01-31 2014-07-31 Sensirion Ag Diffusion based metal oxide gas sensor
US11221430B2 (en) * 2017-01-31 2022-01-11 L&P Property Management Company Multi-frequency landscape analysis system, method, and apparatus for furniture sensing
US11465123B2 (en) * 2009-09-01 2022-10-11 Blue-Zone Technologies Ltd. Systems and methods for gas treatment

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19650897A1 (de) * 1996-12-07 1998-06-10 T E M Tech Entwicklung Und Man Apparat und Verfahren zur Erhöhung der Sicherheit von Atemschutzmasken
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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4146834A (en) * 1974-09-19 1979-03-27 Drexelbrook Controls, Inc. Admittance measuring system for monitoring the condition of materials
US4755473A (en) * 1985-05-16 1988-07-05 Sekisui Kaseihin Kogyo Kabushiki Kaisha Method of detecting carbon dioxide gas
US4770761A (en) 1981-11-12 1988-09-13 U.S. Philips Corporation Sensor for determining the oxygen content in a gas
US4864462A (en) * 1986-06-30 1989-09-05 Sri International Capacitive gas detector having a solid rare earth fluoride dielectric
DE3827426A1 (de) 1988-08-12 1990-02-15 Rump Elektronik Tech Vorrichtung zur durchfuehrung eines verfahrens zum zwecke der identifizierung und quantifizierung unbekannter gasfoermiger substanzen
US4906440A (en) 1986-09-09 1990-03-06 The United States Of America As Represented By The Secretary Of The Air Force Sensor for detecting chemicals
DE3917853A1 (de) 1989-06-01 1990-12-06 Rump Elektronik Tech Gasempfindlicher halbleitersensor mit frequenzabhaengig veraenderter selektivitaet
US5019517A (en) * 1988-04-15 1991-05-28 Coulson Dale M System, detector and method for trace gases
US5387462A (en) 1991-04-05 1995-02-07 Minnesota Mining And Manufacturing Company Sensors based on nanostructured composite films
US5965451A (en) * 1996-07-26 1999-10-12 Dornier Gmbh Lhg Use of a gas sensor for the selective detection of hydrocarbons in low-oxygen gases

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4146834A (en) * 1974-09-19 1979-03-27 Drexelbrook Controls, Inc. Admittance measuring system for monitoring the condition of materials
US4146834B1 (de) * 1974-09-19 1992-09-22 Drexelbrook Controls
US4770761A (en) 1981-11-12 1988-09-13 U.S. Philips Corporation Sensor for determining the oxygen content in a gas
US4755473A (en) * 1985-05-16 1988-07-05 Sekisui Kaseihin Kogyo Kabushiki Kaisha Method of detecting carbon dioxide gas
US4864462A (en) * 1986-06-30 1989-09-05 Sri International Capacitive gas detector having a solid rare earth fluoride dielectric
US4906440A (en) 1986-09-09 1990-03-06 The United States Of America As Represented By The Secretary Of The Air Force Sensor for detecting chemicals
US5019517A (en) * 1988-04-15 1991-05-28 Coulson Dale M System, detector and method for trace gases
DE3827426A1 (de) 1988-08-12 1990-02-15 Rump Elektronik Tech Vorrichtung zur durchfuehrung eines verfahrens zum zwecke der identifizierung und quantifizierung unbekannter gasfoermiger substanzen
DE3917853A1 (de) 1989-06-01 1990-12-06 Rump Elektronik Tech Gasempfindlicher halbleitersensor mit frequenzabhaengig veraenderter selektivitaet
US5387462A (en) 1991-04-05 1995-02-07 Minnesota Mining And Manufacturing Company Sensors based on nanostructured composite films
US5965451A (en) * 1996-07-26 1999-10-12 Dornier Gmbh Lhg Use of a gas sensor for the selective detection of hydrocarbons in low-oxygen gases

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
J. Gutierrez "Sensors and actuators", vol. 4, 1991 pp. 359 to 363.

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7553458B2 (en) 2001-03-05 2009-06-30 Micronas Gmbh Alcohol sensor using the work function measurement principle
US20050029102A1 (en) * 2001-10-04 2005-02-10 Norbert Breuer Sensor for determining the carbon monoxide concentration of a gas mixture
US7812622B1 (en) * 2002-09-09 2010-10-12 Yizhong Sun Sensor and method for detecting analytes in fluids
WO2005095949A1 (en) * 2004-03-31 2005-10-13 Her Majesty The Queen In Right Of Canada As Represented By The Minister Of The Environment Method and apparatus for monitoring catalytic abator efficiency
US20090127100A1 (en) * 2004-04-22 2009-05-21 Maximilian Fleischer Fet-based sensor for detecting reducing gases or alcohol, and associated production and operationg method
US7707869B2 (en) 2004-04-22 2010-05-04 Micronas Gmbh FET-based gas sensor
US20070220954A1 (en) * 2004-04-22 2007-09-27 Micronas Gmbh Fet-Based Gas Sensor
US7992426B2 (en) 2004-04-22 2011-08-09 Micronas Gmbh Apparatus and method for increasing the selectivity of FET-based gas sensors
US7946153B2 (en) 2004-04-22 2011-05-24 Micronas Gmbh Method for measuring gases and/or minimizing cross sensitivity in FET-based gas sensors
US20070181426A1 (en) * 2004-04-22 2007-08-09 Maximilian Fleischer Fet-based sensor for detecting reducing gases or alcohol, and associated production and operation method
US20060218989A1 (en) * 2005-03-30 2006-10-05 Dominic Cianciarelli Method and apparatus for monitoring catalytic abator efficiency
US7772617B2 (en) 2005-03-31 2010-08-10 Micronas Gmbh Gas sensitive field-effect-transistor
US20060260737A1 (en) * 2005-03-31 2006-11-23 Maximilian Fleischer Gas-sensitive field-effect transistor with air gap
US7459732B2 (en) 2005-03-31 2008-12-02 Micronas Gmbh Gas-sensitive field-effect transistor with air gap
US20070235773A1 (en) * 2005-03-31 2007-10-11 Ignaz Eisele Gas-sensitive field-effect transistor for the detection of hydrogen sulfide
US20060278528A1 (en) * 2005-04-01 2006-12-14 Maximilian Fleischer Method of effecting a signal readout on a gas-sensitive field-effect transistor
US20080198524A1 (en) * 2007-02-16 2008-08-21 Dometic Corporation Absorption gas arrestor system
US11465123B2 (en) * 2009-09-01 2022-10-11 Blue-Zone Technologies Ltd. Systems and methods for gas treatment
US20140212979A1 (en) * 2013-01-31 2014-07-31 Sensirion Ag Diffusion based metal oxide gas sensor
US9518970B2 (en) * 2013-01-31 2016-12-13 Sensirion Ag Method for determining analyte type and/or concentration with a diffusion based metal oxide gas sensor
US11221430B2 (en) * 2017-01-31 2022-01-11 L&P Property Management Company Multi-frequency landscape analysis system, method, and apparatus for furniture sensing

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WO1997041423A1 (de) 1997-11-06
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JP3339867B2 (ja) 2002-10-28
EP0896667A1 (de) 1999-02-17
EP0896667B1 (de) 2007-07-11
US20020011851A1 (en) 2002-01-31
ATE366925T1 (de) 2007-08-15
DE19617297A1 (de) 1997-11-13
DE59712858D1 (de) 2007-08-23
BR9708844A (pt) 2000-01-04
CA2256010A1 (en) 1997-11-06

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